From a viewpoint of an efficient operation of a network, there is a concept called a shared mesh network (SMN). In the SMN, a communication path is established through a desired communication node for connection without regard to a network topology such as a linear network (also referred to as an end-to-end network) or a ring network.
In the SMN, a technology called a shared mesh protection (SMP) may be used to achieve the efficiency of a protection line as well as a working line. The terms “working” and “protection” may be referred to as “active” and “standby”, respectively. The term “line” may be referred to as a “path” or a “channel”.
In the SMP, one protection path is used for (or shared by) a plurality of working path. Therefore, the SMP may be considered as a technology called a “1:N protection”.
In a network before the SMN appears, there is a protection scheme such as a “1+1 protection”, a “1:1 protection”, or a “1:N protection”. In the protection scheme, a path having the same condition as a working path is prepared as a “protection path”.
Documents D1 to D5 listed below disclose an online test of a communication path in an LSP (Label Switched Path), a mesh network, and an ATM switch, and a technology relating to the 1:N protection in the mesh network.
D1: JP 2012-500539 T
D2: JP 2007-74314 A
D3: JP 2002-247038 A
D4: JP 7-183889 A
D5: JP 2005-27144 A
According to the technology disclosed in D1 to D5, it may be insufficient for a reliability (it may also be referred to as soundness or failure resistance) of a network (it may also be referred to as a communication system) in some cases.